ipad mini A17: On the home screen- how do you move the settings app to the bottom box next to the safari app.?

Presumably you refer to moving the Settings App icon from the Home Screen to the Dock seen at the bottom of your screenshot. You simply need to drag the Settings App icon to the Dock...

Touch and hold the settings icon. When the icons wobble, simply drag the Settings icon to the dock - and then lift your finger from the screen. Finally, tap any empty area of the Home Screen to finish moving icons.

Should you need additional information, the iPad User Guide is a rich source of information about your iPad and iPadOS. Here is a direct link to the relevant section of the Guide:

Move apps and widgets on the iPad Home Screen - Apple Support

You appear to have successfully added the Settings App to your Dock. As for why you are unable to move items to and from the Dock, as I described, I cannot fathom. The described method works without difficulty on my library of Apple devices - each currently running iPadOS 12/15/17/18.x.

Your screenshot shows very few App icons. Are you using a "managed" iPad - perhaps in an Educational or Enterprise environment?